Swimmer training apparatus having force control

ABSTRACT

A swimmer training apparatus includes a housing having a rotatable spool mounted therein and defining a longitudinal spool axis. The rotatable spool includes a cylindrical outer surface and a spooler is mounted to the housing and adapted to axially advance a swimmer tethering line along the cylindrical outer surface during playing out or taking up the swimmer tethering line. The swimmer training apparatus further includes a torque transfer device coupled between a motor and the rotatable spool and including a magnetic field generator configured to generate a magnetic field. The torque transfer device further includes a rotatable mechanism fixed to rotate with the rotatable spool and a rotatable mechanism fixed to rotate with the motor. One of the rotatable mechanisms includes a magnetically permeable medium adapted via interacting with the magnetic field to transfer a torque between the first rotatable mechanism and the second rotatable mechanism during rotating the rotatable spool. A torque control system for the swimmer training apparatus includes an electronic control unit configured via software and/or hardware control to implement an operating method for training or evaluating performance of a swimmer.

TECHNICAL FIELD

The present disclosure relates generally to systems for athletictraining, instruction or evaluation of a swimmer in a swimming pool, andrelates more particularly to a swimmer training apparatus and strategywhere a controllable assistive or resistive force is applied to aswimmer tethering line.

BACKGROUND

A variety of swimmer training devices are known and have been widelyused for many years. Certain early system utilized vertically movableweight stacks or elastic mechanisms tethered to a swimmer to provide aresistive force as the swimmer swims one direction in a swimming lane,and/or to provide assistive forces as the swimmer swims the otherdirection in the swimming lane. It has been recognized for some timethat performance of swimming athletes can be enhanced by specializedtraining regimens using the resistive or assistive mechanisms describedabove. Conventional systems, however, long suffered from a variety ofdrawbacks, including expense, complexity and inapplicability to certaindesired training regimens.

In an attempt to introduce automation and computer control andmonitoring to swimming training, as had been done earlier in certainother sports, in recent years manufacturers proposed a variety ofmechanisms where a swimmer tethering line is spooled or unspooled abouta rotatable mechanism. The speed of rotation of the rotatable mechanismcould be controlled, and in certain instances brakes were selectivelyapplied to the rotatable mechanism to apply a frictional drag. Thesesystems generally improved over elastic bands, weight stacks and thelike in terms of controllability and applicability to different trainingregimens. However, many swimmers and swimming trainers have viewed suchsystems unfavorably from a performance standpoint as well as expense,reliability and general feel. On the one hand, swimming against africtional drag or a varying speed of the rotatable mechanism may imparta perceived unnatural feel. Moreover, applying a frictional drag doesnot always provide an easy mechanism for gathering and processing dataassociated with a swimmer's performance. Further, while electric motorsmay have a controllable speed, they typically do not provide a variableforce, at least without also varying speed. Further still, existingsystems lack any mechanism for readily determining power output or peakpower output of a swimmer, factors suggested as useful by swimmertraining research.

U.S. Pat. No. 5,391,080 to Bernacki et al. proposes a swim instruction,training and assessment apparatus. Bernacki et al. is representative ofone class of swimmer training systems that, while improving over variousearlier strategies, suffer from certain of the drawbacks discussedabove. Namely, Bernacki et al. does not provide for smoothcontrollability of resistive or assistive forces applied to a swimmer,and does not allow for easy determination of power output or peak poweroutput of a swimmer.

The present disclosure is directed in part to one or more of theproblems or shortcomings set forth above.

SUMMARY

In one aspect, a swimmer training apparatus includes a housing and arotatable spool mounted to the housing and defining a longitudinal spoolaxis. The rotatable spool includes a cylindrical outer spool surface andis configured via rotating in a first direction or a second directionopposed to the first direction for respectively playing out or taking upa swimmer tethering line. The swimmer training apparatus furtherincludes a spooler mounted to the housing and adapted to axially advancea swimmer tethering line along the cylindrical outer spool surfaceduring playing out or taking up the swimmer tethering line. The swimmertraining apparatus further includes a motor mounted within the housingand including a motor output shaft, and a torque transfer device coupledbetween the motor output shaft and the rotatable spool. The torquetransfer device includes a magnetic field generator configured togenerate a magnetic field, a first rotatable mechanism fixed to rotatewith the motor output shaft and a second rotatable mechanism fixed torotate with the rotatable spool. One of the first rotatable mechanismand the second rotatable mechanism includes a magnetically permeablemedium adapted via interacting with the magnetic field to transfer atorque between the first rotatable mechanism and the second rotatablemechanism during rotating the rotatable spool.

In another aspect, a method of operating a swimmer training apparatusincludes applying a torque to a rotatable spool of the swimmer trainingapparatus via a torque transfer device having a first rotatablemechanism fixed to rotate with a motor for rotating the rotatable spooland a second rotatable mechanism fixed to rotate with the rotatablespool. The rotatable spool is configured for playing out or taking up aswimmer tethering line via spooling the swimmer tethering line on acylindrical outer spool surface thereof. The method further includeschanging an electrical energy state of the torque transfer device, andapplying a different torque to the rotatable spool responsive tochanging the electrical energy state of the torque transfer device.

In still another aspect, a torque control system for a swimmer trainingapparatus includes a torque transfer device having an electricallypowered magnetic field generator, a first rotatable mechanism configuredto couple with a motor output shaft of a motor for rotating a rotatablespool adapted for playing out or taking up a swimmer tethering line, anda second rotatable mechanism configured to couple with the rotatablespool. One of the first rotatable mechanism and the second rotatablemechanism includes a magnetically permeable medium adapted viainteracting with the magnetic field to transfer torque between the firstrotatable mechanism and the second rotatable mechanism during rotatingthe rotatable spool. The torque control system further includes a sensorconfigured to monitor at least one of, a swimming distance parameter ora swimming speed parameter, during playing out or taking up the swimmertethering line via rotating the rotatable spool, and a control systemfor controlling torque transfer between the first rotatable mechanismand the second rotatable mechanism during playing out or taking up theswimmer tethering line. The control system includes an electroniccontrol unit coupled with the sensing system and in controlcommunication with the magnetic field generator. The electronic controlunit is configured to vary a torque transfer between the first rotatablemechanism and the second rotatable mechanism at least in part viacontrolling an intensity of the magnetic field responsive to inputs fromthe sensing system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic view of a swimmer training apparatus, accordingto one embodiment;

FIG. 2 is a partially sectioned diagrammatic view of a portion of theswimmer training apparatus of FIG. 1;

FIG. 3 is a diagrammatic illustration in two views of a swimmer trainingapparatus mounted in a use position adjacent a swimming pool, accordingto one embodiment;

FIG. 4 is a graph illustrating signal values over time during an exampletraining/testing routine for a swimmer, according to one embodiment; and

FIG. 5 is a flowchart illustrating an example training/testing routine,according to one embodiment.

DETAILED DESCRIPTION

Referring to FIG. 1, there is shown a diagrammatic view of a swimmertraining apparatus 10 according to one embodiment. Swimmer trainingapparatus 10 includes a housing 12 having a plurality of housing panels,including a bottom housing panel 14, a first side housing panel 16, asecond side housing panel 18, a front housing panel 20 and a backhousing panel 22. A top housing panel (not shown) may be employed toenclose various internal components of swimmer training apparatus 10within housing 12 for protection from water, debris, damage, etc.Swimmer training apparatus 10 may include a power system 30 positionedat least partially within housing 12 and configured to apply force to aswimmer during training or performance evaluation in a swimming pool. Aswill be further apparent from the following description, swimmertraining apparatus 10 may be uniquely configured via hardware and/orcontrol software of power system 30 to enable a variable assistive orresistive force to be applied to a swimmer during swimming in a swimmingpool.

Power system 30 may include a motor 34 such as a permanent magnet orinductance electric motor positioned within housing 12. Motor 34 mayinclude a motor housing 33 and a rotatable motor output shaft 36.Various internal components such as a stator, rotor, bearings, wiringharness, etc., may be positioned within motor housing 33, but areomitted from the present description as they are deemed familiar tothose skilled in the art. Motor 34 may be mounted to bottom housingpanel 14 by way of a motor mount 35 in one embodiment. Bottom housingpanel 14 may have a substantially planar orientation and thus will beunderstood to define a horizontal plane. Motor 34 may define a motoraxis “M” having an orientation parallel to the horizontal plane definedby bottom housing panel 14. A pulley wheel 38 may be fixedly mounted onmotor output shaft 36. While an electric motor provides one practicalimplementation strategy, it should be appreciated that in otherembodiments alternative motor types such as a hydraulic motor or apneumatic motor might be used.

A rotatable spool 52 may be mounted to housing 12, and in the embodimentshown is positioned within housing 12. Rotatable spool 52 may include afirst axial spool end 56 and a second axial spool end 58, and defines alongitudinal spool axis “S”. Spool 52 may be mounted such thatlongitudinal spool axis S is oriented generally parallel bottom housingpanel 14. Spool 52 may further include a spool shaft 60 mounted inhousing 12 and rotatably journaled via a first bearing 62 proximatefirst axial spool end 56 and via a second bearing 64 proximate secondaxial spool end 58. Spool 52 may further include a cylindrical outerspool surface 54. A flexible swimmer tethering line or cord 95 mayinclude a first end 91 a attached to spool 52. Line 95 may be unwrappedor “unspooled” from cylindrical outer spool surface 54 when rotatingspool 52 in a first direction for playing out swimmer tethering line 95,as further described herein. Line 95 may be wrapped or “spooled” ontocylindrical outer spool surface 54 when rotating spool 52 in a seconddirection opposed to the first direction for taking up swimmer tetheringline 95, as further described herein.

A spooler 66 may be mounted to housing 12 adjacent spool 52 and isadapted to axially advance swimmer tethering line 95 along cylindricalouter spool surface 54 during playing out or taking up swimmer tetheringline 95. Spooler 66 may include a spooler rod 68 rotatably journaled inhousing 12 via a first bearing 74 and via a second bearing 76. A shuttle70 may be positioned on spooler rod 68 and movable in a directionparallel longitudinal spool axis S to assist in spooling or unspoolingswimmer tethering line 95 about cylindrical outer surface 54 in a mannerwhich will be familiar to those skilled in the art. To this end, shuttle70 may be internally threaded and spooler rod 68 may be externallythreaded. Other spooler mechanisms might be used without departing fromthe scope of the present disclosure. It may be noted from FIG. 1 thatfront housing panel 20 is viewed edge-on, and may have a generallyvertical orientation relative to bottom housing panel 14 in oneembodiment. Front housing panel 20 may define a feed opening 24 forfeeding/directing swimmer tethering line 95 during spooling orunspooling swimmer tethering line 95. A pulley wheel 72 may be fixedlymounted to spooler rod 68 in one embodiment and configured to rotatespooler rod 68 to enable axially advancing shuttle 70 and thus axiallyadvancing swimmer tethering line 95 on cylindrical outer surface 54. Inone embodiment, pulley wheel 72 may be rotated via an endless belt orchain 78, extending about pulley wheel 72 and also extending aboutanother pulley wheel 82 which is fixedly mounted to and rotatable withspool shaft 60.

System 30 may further include a torque transfer device 40 coupledbetween motor output shaft 36 and spool 52. Torque transfer device 40may include a housing 41, a first rotatable mechanism 46 fixed to rotatewith motor output shaft 36 and a second rotatable mechanism 48 fixed torotate with spool 52. Torque transfer device 40 may further include aset of mounts 42 mounting torque transfer device 40 to bottom housingpanel 14 such that a longitudinal torque transfer device axis “T”defined by torque transfer device 40 is oriented generally parallelbottom housing panel 14. It may be noted from FIG. 1 that longitudinalmotor axis M, longitudinal torque transfer device axis T andlongitudinal spool axis S are each parallel and non-colinear with oneanother, and are each oriented generally parallel the horizontal planedefined by bottom housing panel 14. In other embodiments, an in-lineconfiguration for axes M, T and S might be used. Gear trains or the likemight also be used to rotatably couple together the various componentsdescribed herein.

In one embodiment, torque transfer device 40 may include a pulley wheel44 which is fixedly mounted to first rotatable mechanism 46, and anotherpulley wheel 50 which is fixedly mounted to second rotatable mechanism48. An endless belt or chain 39 may extend about pulley wheel 44 andalso about pulley wheel 38 to fix first rotatable mechanism 46 to rotatewith motor output shaft 36. Another endless belt or chain 51 may extendabout pulley wheel 50 and also about pulley wheel 53 to fix secondrotatable mechanism 46 to rotate with spool 52. It should be appreciatedthat descriptions herein of two elements “fixed to rotate” with oneanother should not be understood to mean that the two elementsnecessarily rotate at the same speed. Rather, “fixed to rotate” meansthat when one of the subject elements rotates, so does the other, with aconstant relative rotational speed between the two. Thus, it will bereadily appreciated that the various pulley wheels depicted in FIG. 1and described herein may have different diameters, and thus rotate atdifferent speeds even where fixed to rotate with one another via anendless belt, chain, etc.

Swimmer training apparatus 10 may further include a control system 200adapted for controlling operation of the various components of swimmertraining apparatus 10 during training a swimmer, as further describedherein. Control system 200 may include an electronic control unit 202having a data processor 204 and a computer readable memory 206. Controlsystem 200 may be in control communication with motor 34, and also incontrol communication with torque transfer device 40. Control system 200may thus turn on motor 34, turn off motor 34, etc. Control system 200may likewise control an electrical energy state of torque transferdevice 40 to control torque transfer between first rotatable mechanism46 and second rotatable mechanism 48, as further described herein.Control system 200 may further be coupled with a power input interface87 which is connected with an electrical plug 88. Power input interface87 will typically include appropriate components such as powerrectifiers, power inverters, etc., for powering the various componentsof swimmer training apparatus 10 from 110 VDC or 220 VDC power supplies.The components of power input interface 87 are conventional, and controlof power input interface 87 to supply various levels of DC or AC currentto components of swimmer training apparatus 10 will take place in aconventional manner. In one embodiment, each of motor 34 and torquetransfer device 40 will be DC powered devices. Power input interface 87may be coupled via appropriate electrical wiring connections with motor34, torque transfer device 40 and any other electrically poweredcomponents of swimmer training apparatus 10. Such connections are deemedconventional, and thus are not specifically illustrated in FIG. 1.

Control system 200 may further include a sensing system 31 whichincludes a speed sensor 84. Speed sensor 84 may be coupled with a pulleywheel 86 driven via belt 51 and may be configured to output sensorsignals to electronic control unit 202 which are indicative of arotational speed of pulley wheel 86, and hence indicative of arotational speed of spool 52. Suitable rotational speed sensors are wellknown and widely used. By way of known techniques, rotational speed ofspool 52 may be used to compute linear speed of a swimmer during playingout or taking up swimmer tethering line 95, for reasons which will beapparent from the following description. Sensing system 31 may furtherinclude a distance sensor 80, such as a toothed wheel mechanism forexample, coupled with spool shaft 60, rod 68 or any other suitablerotating part of apparatus 10. Distance sensor 80 enables electroniccontrol unit 202 to count revolutions of spool 52, for example, and inturn compute a linear swimmer travel distance, again by way of knowntechniques. It should be appreciated that the speed and distance sensormechanisms described herein are illustrative only, and those skilled inthe art will appreciate that a variety of other techniques may be usedfor distance and/or speed sensing, such as optical scanning techniques,electromagnetically sensing magnets embedded in swimmer tethering line95, or a variety of other strategies. Electronic control unit 202 mayfurther be equipped with a timer or clock (not shown) for timing variousswimmer training or evaluation routines, as further described herein. Apower switch (not shown) may be mounted to housing 12 and configured toturn on power to swimmer training apparatus 10 from power inputinterface 87. In addition, a signaling device 32 such as a light havinga plurality of illumination states may be mounted to housing 12 andcontrollably coupled with electronic control unit 202, as furtherdescribed herein.

In one embodiment, control system 200 may be configured by way ofsoftware including computer readable code stored on computer readablememory 206 to operate, monitor and control each of motor 34 and torquetransfer device 40, for executing a variety of swimmer training orevaluation routines, further described herein. It should be appreciatedthat the terms “training,” “testing” and “evaluation” are usedinterchangeably herein, except as otherwise noted. Control system 200may be resident on swimmer training apparatus 10. In other instances,and indeed in one practical implementation strategy, a non-residentcomputer such as a laptop computer may be connected with swimmertraining apparatus 10 during swimmer training, and may actually controlmotor 34 and torque transfer device 40, as well as gather data fromsensing system 31. Thus, while electronic control unit 202 is shownpositioned within housing 10, in other embodiments electronic controlunit 202 might be resident on a computer separate from apparatus 10. Tothis end, a communications link (not shown), such as a hardwired orwireless link, may be a component of control system 200 for connectingwith a non-resident computer. For the sake of clarity and simplicity thepresent description assumes that electronic control unit 202 ispreprogrammed with all of the software required to implement swimmertraining routines as described herein, and is resident on apparatus 10.

Referring also now to FIG. 2, there is shown a partially sectioneddiagrammatic view of certain of the components which are used as atorque control system for swimmer training apparatus 10. Control system200 and motor 34 are shown in block diagram form. Torque transfer device40 is shown in a sectioned view. In one embodiment, torque transferdevice 40 may be a bidirectional torque transfer device. To this end,torque transfer device 40 may be configured to apply an assistive torquefrom motor 34 on spool 52 when rotating spool 52 in a first direction,such as in a take-up mode, as further described herein. Torque transferdevice 40 may further be configured to apply a resistive torque on spool52 when rotating spool 52 in a second direction, such as in a play-outmode, also further described herein. One of first rotatable mechanism 46and second rotatable mechanism 48 may include a magnetically permeablemedium 92. Torque transfer device 40 may further include a magneticfield generator 93. Magnetically permeable medium 92 may be configuredvia interacting with a magnetic field generated via magnetic fieldgenerator 93 to transfer torque between first rotatable mechanism 46 andsecond rotatable mechanism 48.

In one embodiment, magnetic field generator 93 may include anelectrically powered field coil configured to generate a magnetic fieldresponsive to applying an electric current thereto. To this end, acontrol device 43 may be provided which connects with or is a part ofelectrical input interface 87 and is also controllably coupled withelectronic control unit 202. Control device 43 may be used to control amagnitude of electric current to magnetic field generator 93, in turncontrolling an intensity of the magnetic field generated thereby.Magnetic field intensity of the magnetic field will generally bepositively correlated with a magnitude of the electrical currentsupplied to magnetic field generator 93.

It will be recalled that first rotatable mechanism 46 may be fixed torotate with motor output shaft 36. To this end, first rotatablemechanism 46 may be rotatably journaled via a first bearing 99, a secondbearing 98 and a third bearing 97. Second rotatable mechanism 48 may befixed to rotate with spool 52. Second rotatable mechanism 48 may berotatably journaled via second bearing 98 and also via third bearing 97,and each of second bearing 98 and third bearing 97 may contact each offirst rotatable mechanism 46 and second rotatable mechanism 48. A fourthbearing 94 may rotatably journal second rotatable mechanism 48 insupport block 42.

In one embodiment, first rotatable mechanism 46 may be positioned sothat it does not contact second rotatable mechanism 48. First rotatablemechanism 46 may include a magnetic pole structure including an outerpole 89 and an inner pole 90, defining an air gap 91 therebetween.Second rotatable mechanism 48 may include a cup-shaped rotor whichprojects into air gap 91 and includes magnetically permeable medium 92and is thus commonly identified therewith via reference numeral 92. Inone embodiment, rotor 92 may include a solid metallic cup formed of amagnetically permeable metal such as iron, nickel or alloys thereof.During operation of torque transfer device 40, first rotatable mechanism46 may receive an input torque from motor 34. An assistive torque may betransferred within torque transfer device 40 from first rotatablemechanism 46 to second rotatable mechanism 48, and thenceforthtransferred to spool 52. This general mechanism of operation will applywhere motor 34 is used to rotate spool 52 in a take-up mode, as furtherdescribed herein. Where operating in a play-out mode, motor 34 may ormay not rotate. Hence, first rotatable mechanism 46 may be stationary ina play-out mode, but could also be rotating in a direction opposite thatof second rotatable mechanism 48. In a play-out mode, a swimmer may beunspooling swimmer tethering line 95 from spool 52 and, hence, applyinga torque to second rotatable mechanism 48. In such instances, aresistive torque may be transferred within torque transfer device 40from second rotatable mechanism 48 to first rotatable mechanism 46. Therelative magnitude of torque transferred within torque transfer device40 in either of a play-out mode or a take-up mode will relate to anintensity of the magnetic field generated by magnetic field generator93.

It will be recalled that magnetically permeable medium 92 may beconfigured via interacting with the magnetic field generated by magneticfield generator 93 to transfer torque between first rotatable mechanism46 and second rotatable mechanism 48. In one embodiment, torque transferdevice 40 may define a positive electric current to bidirectional torquecapacity correlation coefficient. For example, assume an input torque of“X” Newton-meters is applied from motor 34 to first rotatable mechanism46 when an electric current of “Y” Amperes is supplied to magnetic fieldgenerator 93 at a supply voltage. This might be the case when apparatus10 is operating in a take-up mode and applying an assistive force on aswimmer. A torque transferred to second rotatable mechanism 48 and thusapplied to spool 52 for assisting taking up swimmer tethering line 95will be the input torque of X Newton-meters multiplied by a firstnumeric value which is based on the magnitude of the electric current YAmperes. When an input torque of X Newton-meters is applied to firstrotatable mechanism 46 and an electric current of Y+1 Amperes issupplied to magnetic field generator 93 at the supply voltage, then atorque transferred to second rotatable mechanism 48 and thus applied tospool 52 for assisting taking up swimmer tethering line 95 will be theinput torque of X Newton-meters multiplied by a second numeric valuewhich is based on the magnitude of the electric current Y+1 Amperes. Itwill thus be appreciated that the capacity for transferring torque fromfirst rotatable mechanism 46 to second rotatable mechanism 48 will bepositively correlated with an intensity of the magnetic field generatedby magnetic field generator 93, which is in turn positively correlatedwith a magnitude of the electric current supplied to magnetic fieldgenerator 93. The first numeric value and the second numeric value inthe above examples represent the positive electric current tobi-directional torque capacity coefficient. In other words, the subjectcoefficient is a positive numerical quantity which varies as a functionof electric current magnitude in magnetic field generator 93. In aplay-out mode, where a torque is applied to second rotatable mechanism48 as a swimmer is unspooling swimmer tethering line 95, rotor 92 mayinteract with a magnetic field of controllable intensity generated viamagnetic field generator 93 to resist rotation of spool 52. Applicationof a resistive force thus takes place in a manner analogous toapplication of an assistive force. Where device 40 is used to resistrotation of spool 52, motor 34 may be stationary, or motor 34 may berotating. In some instances, motor 34 might rotate continuouslythroughout both a play-out, resistive mode and a take-up, assistivemode. This capability may enhance a perceived smoothness in operation ofapparatus 10, as it will be unnecessary to start or stop rotation ofmotor 34 during operation.

From the foregoing description, those skilled in the art will appreciatethat torque transfer device 40 may operate as a clutch. In other words,relative rotation may exist between first rotatable mechanism 46 andsecond rotatable mechanism 48. At any given time, regardless of rotationdirection, a magnitude of a torque transferred between first rotatablemechanism 46 and second rotatable mechanism 48 may be positivelycorrelated with a magnitude of an electric current supplied to magneticfield generator 93. The torque capacity of torque transfer device 40will be understood in light of the present description to be themagnitude of torque which can be transferred between first rotatablemechanism 46 and second rotatable mechanism 48 without relative rotationoccurring between the respective components. Since torque transferdevice 40 may be bidirectional, torque transfer device 40 will beunderstood to define the positive electric current to bi-directionaltorque capacity correlation coefficient mentioned above. Determining thesubject coefficient may take place empirically, for example, by varyingtorque(s) applied to one or both of rotatable mechanisms 46 and 48, andvarying electric current magnitude to magnetic field generator 93, andmeasuring a torque transferred between elements 46 and 48.

In one practical implementation strategy, torque transfer device 40 mayinclude a hysteresis clutch. As used herein, the term “hysteresis”clutch should be understood to refer to a class of clutch mechanismsknown in the art that enable torque transfer between two rotatablebodies based predominantly upon interaction of one of the rotatablebodies with a magnetic field of controllable intensity. Suitablehysteresis clutches are available from Magtrol Inc. of Buffalo, N.Y.Other devices might be substituted for a hysteresis clutch withoutdeparting from the scope of the present disclosure. Devices are known,for example, which transfer torque between two rotatable bodies by wayof inducing electrical eddy currents in one of the rotatable bodies.Embodiments are contemplated where an eddy current device is used,however, a hysteresis device as described herein is contemplated to beone practical implementation strategy, as hysteresis clutches tend toprovide a smoothly controllable, robust mechanism for transferringtorque. In still other embodiments, more exotic variable torque transferdevices such as those using electro-rheological fluids and the likemight be substituted for torque transfer device 40. Certain permanentmagnet clutch devices where torque transfer between two bodies is basedon proximity or positioning of a magnetically permeable medium to apermanent magnet could also be used. In still other versions,combinations of multiple clutches or combinations of clutches withbrakes might be used which would still fairly be considered to fallwithin the spirit and scope of the present disclosure.

INDUSTRIAL APPLICABILITY

Referring to FIG. 3, there is shown an illustration of swimmer trainingapparatus 10 mounted in a use position/orientation adjacent an edge of aswimming pool “P”. In one embodiment, swimmer training apparatus 10 maybe positioned upon and secured to a starting block 101. A human swimmeris identified via reference letter W. A swimmer tethering mechanism 81which includes swimmer tethering line 95 and a swimmer tethering harness96 are also shown. A second end 91 b of swimmer tethering line 95connects with swimmer tethering harness 96, whereas a first end 91 ashown in FIG. 1 connects with rotatable spool 52. It should beappreciated that the illustration in FIG. 3 is diagrammatic only, andadditional components of a swimmer training system such as a directionalpulley wheel for directing swimmer tethering line 95 along a surface ofpool P as desired might be used. Moreover, personnel involved intraining a swimmer such as a trainer might utilize a laptop computercoupled with swimmer training apparatus 10, although no such computer isillustrated in FIG. 3.

In FIG. 3, the upper illustration “F” shows swimmer W after havingunspooled an initial segment of swimmer tethering line 95 between astart time to of a training or evaluation cycle and a second time t₁.The lower illustration “G” shows swimmer W after having unspooled asubsequent segment of swimmer tethering line 95 between time t₁ and athird time t₂. Referring also to FIG. 5, there is shown a flowchart 100illustrating an example control routine whereby swimmer trainingapparatus 10 is used in training/evaluating a swimmer and gatheringvarious test data respecting the swimmer's performance.

The process of flowchart 100 may start at step 105, and may thenceforthproceed to step 110 to select and start a ramp force program. The rampforce program may generally involve increasing a resistive force on aswimmer as the swimmer swims in a pool until such time as the swimmer isno longer able to make forward progress due to the resistive force. Theramp force program may be only one of a plurality of programs availablefor implementation via swimmer training apparatus 10, certain of whichare further described below. From step 110, the process may proceed tostep 120 to attach tethering line 95 to swimmer W. From step 120, theprocess may proceed to step 130 to run the selected program.

From step 130, the process may proceed to step 140 to activate thecontroller, such as electronic control unit 202, and thenceforth to step150 to initiate a swim trial. In one embodiment, a signaling device suchas device 32 may be activated to signal to a swimmer to begin swimmingand/or alternatively signal a trainer to verbally command a swimmer tobegin swimming, such as by pushing off from an edge of pool P. Inexecuting the example ramp force program, resistive force applied to aswimmer may be maintained at a constant, relatively low level or a zerolevel for an initial period of the program. It is only after a swimmerhas traveled a specified distance, or after a specified time, that forceramping will typically commence.

FIG. 3 shows in illustration F an example initial distance traveled byswimmer W, after which force ramping will commence. The specifieddistance (or time) may be selected to allow a swimmer to achieve amaximum or optimum speed for ramp force training, achieve a certainstroke cadence, or for other purposes. In any event, however, thespecified distance or time might vary swimmer to swimmer, and/or mightbe determined empirically as an appropriate point to begin forceramping. At step 160, tracking and recording of distance, time, speed,force and power may commence. It will be recalled that electroniccontrol unit 202 may include a timer. In addition, control system 200may include speed sensor 84 and distance sensor 80, for monitoring aswimmer speed parameter and a swimming distance parameter. Computerreadable memory 204 may store a value corresponding to the specifieddistance or time. To determine whether a tracked distance or time isequal to, or greater than, a specified distance or time, electroniccontrol unit 202 may compare a value corresponding to a tracked distanceor time with the value corresponding to the specified distance or time.After a specified time delay, for example, resistive force on swimmer Wmay be gradually increased from zero to or toward maximum resistiveforce in step 170.

In the present example routine, swimmer W is swimming away fromapparatus 10, and will be understood to be unspooling swimmer tetheringline 95 from spool 52. Motor 34 may be rotating or may not be rotating,and swimmer W will be applying a torque on spool 52 which is transferredto second rotatable mechanism 48. Where no electric current is suppliedto magnetic field generator 93, substantially the only forces fromapparatus 10 which resist forward travel by swimmer W will be relativelysmall frictional forces associated with rotating the various componentsof apparatus 10. Hence at step 170, force may be applied andincrementally increased. This means that a resistive force applied toswimmer W may be increased by changing an electrical energy state of atorque control mechanism of torque transfer device 40. In oneembodiment, the torque control mechanism may include magnetic fieldgenerator 93. Changing an electrical energy state of torque transferdevice 40 could include stepping up electrical current supplied tomagnetic field generator 93 from zero to a first current level. Changingan electrical energy state of torque transfer device 40 could alsoinclude stepping up electrical current supplied to magnetic fieldgenerator 93 from a first current level to a second current level. Ineither case, changing the electrical energy state of magnetic fieldgenerator 93 increases a resistive torque applied to second rotatablemechanism 48 from first rotatable mechanism 46. By way of transferringthe resistive torque to spool 52, resistive linear force applied toswimmer W via swimmer tethering line 95 is increased.

From step 170, the process may proceed to step 180 to sense a zeroforward speed, for example based on inputs from speed sensor 84. Oncespeed is equal to zero, it may be concluded that swimmer W is no longertraveling forward, and cannot overcome the resistive linear forceapplied via swimmer tethering line 95. From step 180, the process mayproceed to step 190 to calculate and record stall force, peak speed andpeak power. By measuring speed and force as described herein, power andpeak power may be calculated. Calculating peak power may take place byway of known techniques by measuring the maximum resistive force justprior to where a swimmer ceases to make forward progress. Step 190 mayalso include outputting a peak power signal. Outputting the peak powersignal may include outputting a signal corresponding to the calculatedpeak power from data processor 202, and recording a signal value for thepeak power signal on computer readable memory 204. Test data includingdistance traveled by swimmer W, time duration between t₀ and t₂, thestall force such as the maximum force applied via swimmer tethering line95, and the peak power in watts, as well as other data may be recordedon computer readable memory at step 190. From step 190, the process mayproceed to step 195 to activate retrieval of swimmer W. The process maythen proceed to step 200 and end retrieval. If the routine is to berepeated, the process may proceed to step 197, then return to step 140.If the routine is not to be repeated, the process may proceed to end theprogram at step 202. The process may end at step 205, or may repeat viastep 199 with a new swimmer, as illustrated.

Referring to FIG. 4, there is shown a graph illustrating a plurality ofcurves corresponding to data gathered during executing the routinedescribed in connection with FIGS. 3 and 5 from time t₀ to time t₂. InFIG. 4, curve A corresponds to distance traveled by swimmer W. Curve Bcorresponds to speed of swimmer W. It may be noted that curve B isroughly sinusoidal, corresponding to variations in speed of a typicalswimmer which arise from the swimmer's stroke cadence. Curve Ccorresponds to force applied via swimmer training apparatus 10. It maybe noted that force steadily increases approximately from time t₁ totime t₂. Curve D represents power, and indicates a peak power output ofswimmer W just prior to time t₂ at which the swimmer's speed drops tozero, indicating that forward progress has ceased. It may be noted thatdetermining when a peak power output of swimmer W occurs may be based onboth the speed of swimmer W and the resistive force applied to swimmerW. In other words, peak power output will typically exist just beforethe speed of swimmer W drops to zero.

During operation of swimmer training apparatus, data processor 204 maybe determining values such as control command values for torque transferdevice 40 which are indicative of resistive force applied to swimmer W.In other words, resistive force on swimmer W may be determined based ona known relationship between electrical current commands for magneticfield generator 93 and a torque transferred from first rotatablemechanism 46 to second rotatable mechanism 48. Such a relationship mightbe determined empirically. Where peak power is being determined,determining one or more values indicative of resistive force applied toswimmer W may take place during unspooling the second segment of swimmertethering line 95 from time t₁ to t₂. Data processor 204 may also bedetermining values indicative of a speed of swimmer W, such as viainputs from sensor 84 which represent a rotational speed of spool 52during unspooling swimmer tethering line 95. Where peak power is beingdetermined, determining one or more values indicative of a speed ofswimmer W may therefore also take place during unspooling the secondsegment of swimmer tethering line 95 from time t₁ to t₂. Thus,determining peak power output of swimmer W and outputting the peak powersignal may be understood as taking place in a manner which is responsiveto values indicative of a speed of a swimmer, and also responsive tovalues indicative of resistive torque on spool 52 and thus a resistivelinear force on the swimmer.

As discussed above, the example routine described in connection withFIG. 3 is a ramp force program. Swimmer training apparatus 10 may beused in a variety of other types of programs, including but not limitedto a resistance training swimming program, an assistance trainingswimming program or a resistance and assistance training swimmingprogram. In the first of these, a resistance training mode, swimmertraining apparatus 10 may be operated in a manner similar to that of theramp force program. Rather than ramping force up until a swimmer stalls,however, a constant or varying resistive force can be applied duringplaying out swimmer tethering line 85 via controlling torque transferdevice 40 as described herein. The smoothly controllable resistive forceapplied via torque transfer device 40 may allow force to be varied insome embodiments based on a swimmer's stroke cadence. For example,resistive force could be increased and decreased in opposition to aswimmer's increasing and decreasing swimming force which occurs as theswimmer strokes through the water. In an assistance training mode, motor34 may be used to assist a swimmer by providing an assistive torqueduring taking up swimmer tethering line 95. The assistive torque mayalso be varied by way of controlling torque transfer device 40 asdescribed herein. In a resistance and assistance training mode, aresistive torque may be applied while a swimmer is unspooling swimmertethering line 95, and then an assistive torque may be applied whilemotor 34 is activated to take up or spool swimmer tethering line 95.

It should be appreciated that in any of the modes described herein,torque may be applied to spool 52 via controlling torque transfer device40 as described herein. A first torque may be applied during unspoolinga first segment of swimmer tethering line 95, and then increased ordecreased during unspooling a second segment of swimmer tethering line95. Thus, by way of the illustrations of FIG. 3, it will be understoodthat a first torque corresponding to a first resistive force might beapplied from time t₀ to t₁, whereas a second, greater or lesser torque,corresponding to a second, different resistive force might be appliedfrom time t₁ to t₂. Similarly, when a swimmer turns around and beginsswimming back toward apparatus 10, a first assistive force might beapplied during taking up or spooling a first segment of swimmertethering line 95, whereas a second, greater or lesser, assistive forcemight be applied during taking up or spooling a second segment ofswimmer tethering line 95. During taking up or spooling swimmertethering line 95, motor 34 may be operated at a constant speed.

The present disclosure differs from state of the art swimmer trainingsystems and strategies where torque control is limited generally tobraking rotating components of the system. Moreover, while certainsystems might claim to control force on a swimmer, true force control inknown systems is often limited to controlling a force applied duringtaking up a swimmer tethering line, and takes place only by way ofattempting to control a force applied via a take-up motor. By using atorque transfer device as described herein, torque control and, hence,application of force on a swimmer tethering line is smoothlycontrollable during either of taking up or playing out a swimmertethering line. During taking up or playing out a swimmer tetheringline, motor 34 may operate at constant speed, with force control takingplace purely by way of controlling torque transfer device 40. Theseattributes of apparatus 10 are considered to provide various advantagesover state of the art systems. Apparatus 10 not only enables trainingroutines that are otherwise possible, if at all, only by way of complex,expensive and unwieldy mechanisms, but also enables obtaining test datafor a swimmer such as peak power that are not possible with conventionalsystems.

The present description is for illustrative purposes only, and shouldnot be construed to narrow the breadth of the present disclosure in anyway. Thus, those skilled in the art will appreciate that variousmodifications might be made to the presently disclosed embodimentswithout departing from the full and fair scope and spirit of the presentdisclosure. Other aspects, features and advantages will be apparent uponan examination of the attached drawings and appended claims.

1. A swimmer training apparatus comprising: a housing; a rotatable spoolmounted to the housing and defining a longitudinal spool axis, therotatable spool having a cylindrical outer spool surface and beingconfigured via rotating in a first direction or a second directionopposed to the first direction for respectively playing out or taking upa swimmer tethering line; a spooler mounted to the housing and adaptedto axially advance a swimmer tethering line along the cylindrical outerspool surface during playing out or taking up the swimmer tetheringline; a motor mounted within the housing and including a motor outputshaft; and a torque transfer device coupled between the motor outputshaft and the rotatable spool and including a magnetic field generatorconfigured to generate a magnetic field, a first rotatable mechanismfixed to rotate with the motor output shaft and a second rotatablemechanism fixed to rotate with the rotatable spool, one of the firstrotatable mechanism and the second rotatable mechanism including amagnetically permeable medium adapted, via interacting with a magneticfield generated by the magnetic field generator, to transfer a torquebetween the first rotatable mechanism and the second rotatable mechanismduring rotating the rotatable spool.
 2. The swimmer training apparatusof claim 1 wherein the first rotatable mechanism does not directlycontact the second rotatable mechanism, and wherein the torque transferdevice provides bi-directional torque transfer where the magneticallypermeable medium is adapted via interacting with the magnetic field toapply a resistive torque to the rotatable spool during rotating therotatable spool in the first direction or an assistive torque duringrotating the rotatable spool in the second direction.
 3. The swimmertraining apparatus of claim 2 wherein the magnetic field generatorincludes an electrically powered magnetic field coil configured togenerate the magnetic field responsive to an electric current applied tothe magnetic field coil, and wherein a magnitude of a torque transferredbetween the first and second rotatable mechanisms is positivelycorrelated with a magnitude of the electric current.
 4. The swimmertraining apparatus of claim 2 wherein the motor includes an electricmotor defining a longitudinal motor axis, wherein the torque transferdevice defines a longitudinal torque transfer device axis and whereinthe longitudinal motor axis, the longitudinal torque transfer deviceaxis and the longitudinal spool axis are each parallel and non-colinearwith one another.
 5. The swimmer training apparatus of claim 4 whereinthe rotatable spool is positioned within the housing.
 6. The swimmertraining apparatus of claim 4 wherein the housing further includes abottom housing panel defining a horizontal plane, a back housing paneland a front housing panel, the front housing panel having a generallyvertical orientation relative to the horizontal plane and defining afeed opening positioned adjacent the spooler and adapted for feeding theswimmer tethering line to or from the rotatable spool during taking upor playing out the swimmer tethering line.
 7. The swimmer trainingapparatus of claim 2 wherein the first rotatable mechanism includes apole structure having an inner pole and an outer pole defining an airgap therebetween, wherein the second rotatable mechanism comprises arotor which includes the magnetically permeable medium, and wherein therotor includes a solid magnetically permeable metallic cup projectinginto the air gap.
 8. The swimmer training apparatus of claim 2 whereinthe torque transfer device performs as a clutch.
 9. The swimmer trainingapparatus of claim 8 wherein the torque transfer device performs as ahysteresis clutch.
 10. The swimmer training apparatus of claim 9 whereinthe first rotatable mechanism is fixed to rotate with the motor outputshaft via a first endless belt and the second rotatable mechanism isfixed to rotate with the spool via a second endless belt.
 11. A methodof operating a swimmer training apparatus comprising: applying a firsttorque to a rotatable spool of the swimmer training apparatus via atorque transfer device having a first rotatable mechanism fixed torotate with a motor and a second rotatable mechanism fixed to rotatewith the rotatable spool, the rotatable spool being configured forplaying out or taking up a swimmer tethering line via spooling orunspooling the swimmer tethering line on a cylindrical outer spoolsurface of the rotational spool; changing an electrical energy state ofa torque control mechanism of the torque transfer device; and applying asecond torque different from the first torque to the rotatable spool inresponse to a change in the electrical energy state of the torquecontrol mechanism.
 12. The method of claim 11 wherein the torquetransfer device performs as a clutch, the first rotatable mechanismincludes a field coil configured to generate a magnetic field and thesecond rotatable mechanism includes a rotor having a magneticallypermeable medium configured via interacting with the magnetic field totransfer a torque between the first rotatable mechanism and the secondrotatable mechanism during rotation of the rotatable spool, and whereinchanging an electrical energy state of the torque transfer devicefurther includes changing an electrical energy state of the field coil.13. The method of claim 12 further comprising unspooling a swimmertethering line from the cylindrical outer spool surface of the rotatablespool, and wherein at least one of applying a first torque to therotatable spool and applying a second torque to the rotatable spoolincludes applying a resistive torque during unspooling of the swimmertethering line.
 14. The method of claim 13 wherein applying a firsttorque further includes applying a relatively lesser resistive torqueduring unspooling a first segment of the swimmer tethering line andwherein applying a second torque further includes applying a relativelygreater resistive torque during unspooling a second segment of theswimmer tethering line.
 15. The method of claim 14 further comprising:determining a first value indicative of a rotational speed of therotatable spool during unspooling the second segment of the swimmertethering line; determining a second value indicative of a resistivetorque applied to the rotatable spool during unspooling the secondsegment of the swimmer tethering line; and outputting a peak powersignal responsive to the first value and the second value.
 16. Themethod of claim 15 further comprising spooling a swimmer tethering lineonto the cylindrical outer surface of the rotatable spool, and whereineach of applying a first torque to the rotatable spool and applying asecond torque to the rotatable spool further include applying anassistive torque during spooling the swimmer tethering line.
 17. Atorque control system for a swimmer training apparatus comprising: atorque transfer device including an electrically powered magnetic fieldgenerator configured to generate a magnetic field, a first rotatablemechanism configured to couple with a motor output shaft of a motor anda second rotatable mechanism configured to couple with a rotatable spooladapted for playing out or taking up a swimmer tethering line, one ofthe first rotatable mechanism and the second rotatable mechanismincluding a magnetically permeable medium adapted via interacting withthe magnetic field to transfer torque between the first rotatablemechanism and the second rotatable mechanism during rotating therotatable spool; a sensing system including a sensor configured tomonitor at least one of, a swimming distance parameter or a swimmingspeed parameter, during playing out or taking up the swimmer tetheringline via rotating the rotatable spool; and a control system forcontrolling torque transfer between the first rotatable mechanism andthe second rotatable mechanism during playing out or taking up theswimmer tethering line, the control system including an electroniccontrol unit coupled with the sensing system and in controlcommunication with the magnetic field generator; wherein the electroniccontrol unit is configured to vary a torque transfer between the firstrotatable mechanism and the second rotatable mechanism at least in partvia controlling an intensity of the magnetic field responsive to inputsfrom the sensing system.
 18. The torque control system of claim 17wherein the torque transfer device performs as a hysteresis clutch.